For many applications in the field of robotics, in particular in the field of telemanipulation, there is a need for input devices that can be moved translationally or rotationally. In the case of telemanipulation the movements of the input device are detected and converted into translational and/or rotational movements of one or more manipulators.
A manipulator is, according to DIN EN ISO 8373, an automatically controlled, freely programmable multi-purpose manipulator, which is programmable in three or more axes, and can be arranged in either a fixed location or in a moveable manner for use, for example, in automatic control technology. A manipulator has grippers, tools or workpieces. Manipulators are also used in the field of medicine, for example, in minimally invasive surgery. In the latter case the manipulator can have a laparoscopic instrument and can process very small structures or enable minimally invasive imaging by holding and guiding an endoscope.
Depending on the application, it may no longer be necessary at certain times or in response to events, such as, for example, due to a signal of a deadman switch or leaving the working space of the manipulator, to convert a user input directly into a manipulator movement. Such an interruption of the conversion of the user inputs into manipulator movements is hereinafter referred to as “decoupling”. As a result, after decoupling it may be necessary to allow at a specified time or in response to a specific event the user inputs to be converted again into manipulator movements. This is referred to hereinafter as “coupling”.
If the input device or an arm of the manipulator is moved during the decoupled state, then the position and orientation (pose) of the input device and the corresponding, commanded position and orientation (pose) of the manipulator are no longer synchronized. In this case re-coupling would result in an uncontrolled movement of the manipulator into the position and orientation (pose), currently commanded by the input device. Such an uncontrolled movement of a manipulator is undesirable or inadmissible for a safe operation.
The position is determined by means of information with respect to all three translational degrees of freedom and, thus, the location of a point in space. The orientation is determined by means of information with respect to all three degrees of rotational freedom. The combination of position and orientation of an object is referred to as the pose. In order to determine the pose of a point, the point is assigned three spatial axes. In this way all of the six possible degrees of freedom of the point can be determined.
The published document EP I 876 505 A1 discloses input devices that are equipped with motors or brakes with active axes in order to prevent the input device from moving into the decoupled state. This arrangement makes it possible to hold the input device in the current pose even after decoupling. However, such input devices with active axes are expensive, technically complex and error-prone.
Therefore, the object of the present invention is to enable with simpler means a safe coupling and decoupling of the input device to and from the manipulator. Moreover, the user should be able to operate the system intuitively, and the system should enable a coupling that is as fast and safe as possible.